Phosphatidylinositol 3-Kinases (PI3K) are a large family of lipid kinases involved in cell signaling. The PI3K-AKT pathway is activated in a number of tumour types, resulting in abnormalities of cell growth, proliferation and survival (add ref of 1 recent review). Recently, mutations in the catalytic subunit of the class 1A PI3K (PIK3CA) have been identified in human cancers[1]. The precise role of these mutations in carcinogenesis is still to be clearly defined but with ongoing development of a number of targeted PI3K inhibitors, detection of mutations will become increasingly important for patient selection. Technical challenges in the detection of such mutations result from the limitations of tumour biopsies that may only contain small quantities of the mutated sequences. Furthermore, DNA extracted from paraffin embedded tissue is often degraded and of poor quality. The minimum level of mutant DNA required for detection by sequencing is 15-25% and so there is a pressing need for development of sensitive assays able to detect small amounts of mutated alleles in a heterogenous sample and the products necessary for carrying out the assays.
The present invention seeks to address this need.